1. Field
The disclosure relates to an imaging technology. More particularly, the disclosure relates to a system and a method for displaying a real or virtual scene capable of generating high image quality three-dimensional (3D) images while addressing a vergence-accommodation conflict.
The disclosure enables a user to be immersed in a virtual reality (VR) of various tasks, such as 3D modeling, navigation, design, and entertainment. The disclosure may be employed in various head-mounted devices (HMDs), such as VR glasses or helmets, which are being increasingly used in game and education industries at the moment.
2. Description of Related Art
This section is not provided to describe the technical features of the disclosure, and thus the technical features of the disclosure are not limited by this section. This section is to provide the outline of the related art, which belongs to the same technical field as the disclosure, to those of ordinary skill in the art and to thereby make clear the technical importance due to differences between the related art and the disclosure.
Recently, VR technology has been increasingly used in various fields of life within human society (traditional and well-known applications in game and education industries). To popularize the VR technology and provide for its long-term application, it is necessary to provide a visually comfortable interaction between users and reality.
Modern VR displays support various cues of human vision, for example, motion parallax, binocular disparity, binocular occlusion, and vergence. However, an accommodation cues of a human eye for virtual objects is not supported by these displays. This causes a phenomenon called vergence-accommodation conflict to occur. The vergence-accommodation conflict occurs because a human vision system needs to maintain a certain focal distance of eyeball lenses when viewing a 3D image, in order to focus on an image formed and viewed by a display or a lens, while simultaneously a user has to change focal distances of the eyeball lenses based on distances to a virtual object according to the current movement of his or her eyes. In other words, the vergence-accommodation conflict occurs since virtual objects are viewed as if the virtual objects were located at different “distances”, but the virtual objects actually exist on a flat surface of a display screen abreast of each other. This conflict between a virtual sequence and reality causes visual discomfort, eye fatigue, eye tension, and headache.
At the moment, light field display technology aiming at addressing the issues of negative effects by delivering the same light as normally received by eyes to the eyes under similar conditions to those of a real life has been being developed.
An embodiment of such a display is disclosed in US 2014/0063077. In more detail, this document discloses a display apparatus including one or more light attenuation layers of which addresses are spatially assignable, and a controller configured to perform computations needed to control the display apparatus, and to address an optimization issue by using weighted nonnegative tensor factorization (NTF) for memory-efficient representation of a light field at a low density. This NTF requires high costs. Furthermore, known apparatuses have no mobility and cannot be head-mounted.
An embodiment of the disclosure is disclosed in paper “The Light-Field Stereoscope: Immersive Computer Graphics via Factored Near-Eye Light Field Displays with Focus Cues (ACM SIGGRAPH, Transactions on Graphics 33, 5, 2015)” by F. Huang, K. Chen, and G. Wetzstein. This paper discloses a portable VR display supporting an initial high resolution image and the possibility of focusing a user's eyes on a virtual object, that is, the possibility of addressing the vergence-accommodation conflict. A light field appears on each eye, and a more natural visual experience than that in existing near-eye displays is provided through the light field. The proposed display uses rank-1 light field factorization. To implement the display described above, an expensive time-division multi-image display or eye tracking unit is not required. However, the authors of the paper used computationally complicated non-negative matrix factorization (NMF) for a solution.
Therefore, a need exists for a display system, e.g., a head-mountable display suitable for a VR application, capable of addressing the vergence-accommodation conflict while generating a high-quality image.
The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure.